How to determine looseness in a machine

[machinedoc]

Can anybody tell how to determine from the vibration spectrum that the fault is looseness (structure or part)?

[fraz]

In a spectrum looseness is indicated by the harmonics at mutiples of machine running frequency. For example if a machine is ritating at 3000 rpm, if vibration is appearing at 3000 rpm, 6000 rpm, 9000 rpm and so on, then it is structural or part looseness

[yahoo]

A good way to check looseness is by taking phase readings at different points and comparing them with the adjacent components.

[fraz]

Yes, you have rightly explained this is true for structural looseness